feat: generation options for infer.py, and split out training deps

infer.py could only render a random example from examples/input_params:
there was no way to pass your own prompt, lyrics, duration or seed, so
using it for anything specific meant writing a separate script. Add
--prompt, --lyrics/--lyrics_file, --duration, --steps, --guidance_scale,
--scheduler, --cfg_type, --omega_scale, --seed and --format alongside the
existing runtime flags. Without --prompt the old random-example behaviour
is kept, so existing invocations are unaffected.

Also move the training-only packages out of the default install.
datasets, pytorch_lightning, matplotlib, tensorboard and tensorboardX are
imported by trainer.py and convert2hf_dataset.py, never on the inference
path, but every user was installing them — and datasets==3.4.1 is a hard
pin that drags constraints onto huggingface-hub. They now live in
requirements-train.txt behind the existing (previously ineffective)
"train" extra: pip install -e ".[train]".

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

setup.py

@@ -1,5 +1,16 @@
 from setuptools import setup, find_namespace_packages
 
+
+def read_requirements(path):
+    """Read a requirements file, skipping comments and blank lines."""
+    with open(path, encoding="utf-8") as f:
+        return [
+            line.strip()
+            for line in f
+            if line.strip() and not line.lstrip().startswith("#")
+        ]
+
+
 setup(
     name="ace_step",
     description="ACE Step: A Step Towards Music Generation Foundation Model",
@@ -7,7 +18,7 @@ setup(
     long_description_content_type="text/markdown",
     version="0.2.0",
     packages=find_namespace_packages(),
-    install_requires=open("requirements.txt", encoding="utf-8").read().splitlines(),
+    install_requires=read_requirements("requirements.txt"),
     author="ACE Studio, StepFun AI",
     license="Apache 2.0",
     classifiers=[
@@ -25,10 +36,7 @@ setup(
         "acestep.models.lyrics_utils": ["vocab.json"],  # Specify the relative path to vocab.json
     },
     extras_require={
-        "train": [
-            "peft",
-            "tensorboard",
-            "tensorboardX"
-        ]
+        # Only needed to train or fine-tune; inference does not import these.
+        "train": read_requirements("requirements-train.txt"),
     },
 )